In recent years, fibrous carbon nanostructures such as carbon nanotubes (hereinafter, also referred to as “CNTs”) have been attracting interest as materials having excellent electrical conductivity, thermal conductivity, and mechanical properties.
However, fibrous carbon nanostructures such as CNTs are fine structures having nanometer-size diameters, and thus individual fibrous carbon nanostructures have poor handleability and processability. Accordingly, it has been proposed that, for example, a plurality of CNTs may be aggregated into the shape of a film to form a carbon nanotube film (hereinafter, also referred to as a “CNT film”), which is sometimes referred to as “buckypaper”, and this CNT film may be used as a conductive film or the like. More specifically, it has been proposed that a carbon film formed by removing a solvent from a dispersion liquid obtained by mixing the solvent and fibrous carbon nanostructures, such as CNTs, and dispersing the fibrous carbon nanostructures by stirring, or the like may be used as a component (for example, a conductive film or a catalyst layer) of an electrode in a solar cell, touch panel, or the like (for example, refer to PTL 1).
Carbon films obtained through aggregation of fibrous carbon nanostructures into a film shape as described above are attracting interest as film materials having excellent properties in terms of electrical conductivity, thermal conductivity, mechanical properties, and so forth.